Ricardo Cruz, 25, is accused of robbing people at the same ATM -- in the vestibule of the Washington Savings Bank at Middlesex and Central streets in downtown Lowell. He was taken into custody Wednesday.

Police said Tuesday that they were worried that he was getting more aggressive. In the last incident, he is accused of holding a knife to the throat of the victim.

A $2,000 reward was offered for information leading to an arrest and conviction.